Friedel Crafts reaction benzene with sulfur

Friedel-Grafts Reaction. Until quite recently, the manufacture of anthraquiaone ia the United States was by the Friedel-Crafts reaction benzene [71-43-2] and phthaUc anhydride [85-44-9] condense ia the preseace of anhydrous aluminum chloride to give o-benzoylbenzoic acid [85-52-9] which, on treatment with concentrated sulfuric acid, is converted iato anthraquiaoae ia high yields and purity (33). 

The reaction of various A-tosylated a-amino acids (94) with benzene in concentrated sulfuric acid yielded diphenyl derivatives (95)." The mechanism proposed for the reaction (Scheme 9) involves initial protonation of the carboxyl group to give (96), which suffers decarbonylation to the A-tosyliminium salt (97). This reactive electrophile (97) interacts with benzene to give a monophenyl compound (98) which, via a Friedel-Crafts reaction, interacts with another molecule of benzene to yield the diphenyl compound (95)." Toluene and p-xylene reacted analogously to yield diarylated products. 

Thio- and selenoacetals and esters are excellent substrates for mild Friedel-Crafts reactions, because of the affinity of sulfur and selenium for copper (Sch. 23). Anisole was readily acylated with methylselenoesters 94 at room temperature with activation by CuOTf to affordpnra-substituted (> 95 %) derivatives 95 [50,51]. Mercury(II) and copper(II) salts, which were effective for the activation of selenyl esters for reaction with alcohols, amines, and water, were not effective for the Friedel-Crafts reaction. Aromatic heterocycles 96 could be acylated in high yields, and the alkylation product 100 was obtained from dibutylthioacetal 99 and anisole. Vedejs has utilized this methodology in the cyclization of 101 to afford 102 in 77 % yield [52]. This intramolecular variant did not require the use of the more reactive bis copper triflate-benzene complex. 

Commercial benzene (bp 80°) and toluene (bp 111°) contain thiophene and methylthiophene as the main impurities. These impurities are more reactive than benzene or toluene in aromatic substitution reactions and therefore should be removed before using the material for reactions such as the Friedel-Crafts reaction. The thiophenes may be removed by shaking or stirring the hydrocarbon with one-tenth its volume of concentrated sulfuric acid for one-half hour. Because of the reactivity of toluene, the temperature should be maintained under 35° by occasional cooling. This treatment is, however, rarely necessary since thiophene-free benzene and toluene are commercially available at a reasonable cost. 

Subsequently, MBH adducts were successfully utilized as novel stereodefined electrophiles in the Friedel-Crafts reaction with benzene in the presence of a Lewis acid " and sulfuric acid, leading to the stereoselective synthesis of (Z)- and ( )-functionalized trisubstituted alkenes. Notably, MBH adducts obtained from acrylonitrile provide high (Z)-stereoselectivities, while adducts derived from methyl acrylate and aromatic aldehydes give high ( )-stereo-selectivities. When the MBH adducts drived from methyl acrylate and aliphatic aldehydes were involved in the Friedel-Crafts reaction, no significant stereoselectivity was observed (Scheme 3.29). 

Styrene is obtained almost exclusively from the catalytic dehydrogenation of ethyl benzene (600°C, metal oxide). Ethyl benzene is obtained by a Friedel-Crafts reaction of benzene with ethylene. The separation of the styrene from the tetrafunctional, and therefore cross-linkable, divinyl benzene is important. In order to prevent premature polymerization, sulfur or dinitrophenols are added before distillation and t-butyl catechol is added before storing. 

In the preceding section, benzene reacted with cations to form substituted benzene derivatives. The cations of interest include Br+, C1+, the nitronium ion, and sulfur trioxide or sulfuric acid, which react as electrophiles. In principle, benzene may react with any cation, including carbocations, once that cation is formed. Carbocations are generated by several different methods they react with nucleophiles, as described for reactions of alkenes with acids such as HX (Chapter 10, Section 10.2) and for S l reactions (Chapter 11, Section 11.4). If benzene reacts with a carbocation, a new carbon-carbon bond is formed, and electrophilic aromatic substitution will give an arene. The reaction of benzene and its derivatives with carbocations is generically called the Friedel-Crafts reaction, after the work of French chemist Charles Friedel (France 1832-1899) and his American protege, James M. Crafts (1839-1917). The reaction takes two fundamental forms Friedel-Crafts alkylation and Friedel-Crafts acylation. Both variations will be discussed, beginning with the alkylation reaction. 

An alternative route to anthraquinone, which involves Friedel-Crafts acylation, is illustrated in Scheme 4.3. This route uses benzene and phthalic anhydride as starting materials. In the presence of aluminium(m) chloride, a Lewis acid catalyst, these compounds react to form 2-benzoyl-benzene-1-carboxylic acid, 74. The intermediate 74 is then heated with concentrated sulfuric acid under which conditions cyclisation to anthraquinone 52 takes place. Both stages of this reaction sequence involve Friedel-Crafts acylation reactions. In the first stage the reaction is inter-molecular, while the second step in which cyclisation takes place, involves an intramolecular reaction. In contrast to the oxidation route, the Friedel-Crafts route offers considerable versatility. A range of substituted... 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates involve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when catalyzed by aluminum chloride to give Friedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene in propane with sulfuric acid (60). 

Two of the reactions that are used in the industrial preparation of detergents are electrophilic aromatic substitution reactions. First, a large hydrocarbon group is attached to a benzene ring by a Friedel-Crafts alkylation reaction employing tetrapropene as the source of the carbocation electrophile. The resulting alkylbenzene is then sulfonated by reaction with sulfuric acid. Deprotonation of the sulfonic acid with sodium hydroxide produces the detergent. 

The synthetic detergents industry originated in the 1940s, when it was found that a new anionic surfactant type—alkylbenzene sulfonate—had detergent characteristics superior to those of natural soaps. The first surfactant of this kind was sodium dodecylbenzene sulfonate (SDBS). This material was produced by the Friedel-Crafts alkylation reaction of benzene with propylene tetramer (a mixture of Co olefin isomers), followed by sulfonation with oleum or sulfur trioxide and then neutralization, usually with sodium hydroxide. The alkylation was typically performed using homogenous acid catalysts, such as HF or sulfuric acid. 

TP here are very few examples in the literature of poly (arylene polysulfides). Perhaps the first such preparation was that of Fried el and Crafts (I), in which benzene reacted with sulfur in the presence of aluminum chloride. Within the last 15 years, several poly(arylene polysulfides) have been prepared by related reactions in which various aromatic compounds reacted with sulfur monochloride in the presence of Friedel-Crafts catalysts (2, 3, 4). A variation of this reaction has also been reported using a bifiunctional sulfenyl chloride (5) ... 

The reaction was found particularly useful as a relatively selective and mild nitration method, for example allowing mononitration of durene and other highly alkylated benzenes, which with mixed acid usually undergo dinitration. (Table XIl). Methyl nitrate-boron trifluoride can also be used to achieve dinitration of tet-ramethylbenzenes by using two and three molar excess of methyl nitrate, respectively. Relative yields of mono- and dinitro product compositions are shown in Table XIII. Other Friedel-Crafts type catalysts can also be used, but boron trifluoride was found to be the most suitable. Aluminum trichloride and titanium (IV) chloride in the nitration of pentamethylbenzene caused formation of significant amounts of chlorinated derivatives, whereas sulfuric acid led to nitrodemethylation products. 

In the cumene process, benzene is first converted, via the action of propene, to isopropylbenzene (cumene) in a Friedel-Crafts type reaction. Catalysts such as AICI3, sulfuric acid, or phosphoric acid are necessary. Treating cumene with oxygen results in the formation of a hydroperoxide at the tertiary C atom, and this can be decomposed to phenol and acetone. 

Since very few investigations of this reaction have been reported, a short review seems in order. The reaction of benzene and sulfur with AlCl was reported first by Friedel and Crafts in 1878, their eighth paper involving use of AlCl in organic chemistry, and this information was included... 

Anionic surfactants with the general structure RpCONH-X-COONa (e.g., X = -(0112)5-) have been reported in the patent literature. These surfactants are synthesized from the corresponding isopropyl ester and 6-amino-hexanoic acid sodium or ammonium salt (H2N(CH2) 5COOM). Another class of anionic surfactants derived from PFCA derivatives are perfluoroacylbenzenesulfo-nates (Scheme 18.11). This group of surfactants is synthesized by Friedel-Crafts acylation of benzene with a PFCA halide (e.g., perfluorooctanoyl chloride) in the presence of at least one equivalent of a Lewis acid (e.g., anhydrous aluminum chloride). This reaction proceeds smoothly and in good yields at subambient or ambient temperatures. The perfluoroacylbenzene is sulfonated with oleum or sulfur trioxide and neutralized with a base (e.g., sodium hydroxide). 

Friedel-Crafts type alkylations occur in systems other than alkyl halides. When 2-methyl-l-propene is treated with a catalytic amount of sulfuric acid in the presence of benzene, for example, an alkylbenzene is formed. Draw that product and draw a mechanism for its formation. Similarly, when tert-butanol is treated with a catalytic amount of sulfuric acid in the presence of toluene, a Friedel-Crafts type reaction occurs. Draw the product or products of this reaction and give a mechanism for its or their formation. 

The following reactions were used for the industrially important benzene hexachloride with zinc or, better, magnesium, in glacial acetic acid, benzene hexachloride is dechlorinated to benzene, which can then be detected by the Janovsky or Mohler color reaction (p. 356) (18—20). Also, the test proposed for DDT, i.e., nitration and the reaction of the nitro compoimds formed with methanolic sodium hydroxide, is recommended (21). Other tests recommended are the reaction of DDT with sulfuric acid in acetic acid (22), the reaction with xanthydrol, alkali, and pyridine (23), and the reaction with benzene according to the Friedel-Crafts procedure (24). 

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